Presently, there are certain devices available that use piezoelectric active materials to sense various events. Energy pulses from these devices are generally very low in voltage and require the monitoring circuit to be in an “ON” state, generally incorporating an amplifier to allow the circuit to recognize a sensed event. Previous devices for sensing use a significant amount of continuous energy (quiescent current).
Numerous piezoelectric sensors exist. In general, these sensors fall into two overlapping categories. They either require an amplifier to boost the signal from the piezoelectric material, or require a bias signal from which the piezoelectric material's signal subtracts or adds. Each of these techniques requires that the sensor be “ON,” drawing current at all times. Thus, a need exists for a sensor that can avoid the use of an amplifier or a bias signal.
Because a piezoelectric event generally produces only small amounts of energy, the detection of low frequency events has previously required significant amplification. Thus, a need exists for a sensor that can detect low frequency events without the aid of amplification.